package org.apache.solr.search.function.distance;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.solr.search.function.ValueSource;
import org.apache.solr.search.function.DocValues;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.spatial.geohash.GeoHashUtils;

import java.util.Map;
import java.io.IOException;

/**
 * Takes in a latitude and longitude ValueSource and produces a GeoHash.
 * <p/>
 * Ex: geohash(lat, lon)
 * 
 * <p/>
 * Note, there is no reciprocal function for this.
 **/
public class GeohashFunction extends ValueSource {
	protected ValueSource lat, lon;

	public GeohashFunction(ValueSource lat, ValueSource lon) {
		this.lat = lat;
		this.lon = lon;
	}

	protected String name() {
		return "geohash";
	}

	@Override
	public DocValues getValues(Map context, IndexReader reader)
			throws IOException {
		final DocValues latDV = lat.getValues(context, reader);
		final DocValues lonDV = lon.getValues(context, reader);

		return new DocValues() {

			@Override
			public String strVal(int doc) {
				return GeoHashUtils.encode(latDV.doubleVal(doc),
						lonDV.doubleVal(doc));
			}

			@Override
			public String toString(int doc) {
				StringBuilder sb = new StringBuilder();
				sb.append(name()).append('(');
				sb.append(latDV.toString(doc)).append(',')
						.append(lonDV.toString(doc));
				sb.append(')');
				return sb.toString();
			}
		};
	}

	@Override
	public boolean equals(Object o) {
		if (this == o)
			return true;
		if (!(o instanceof GeohashFunction))
			return false;

		GeohashFunction that = (GeohashFunction) o;

		if (!lat.equals(that.lat))
			return false;
		if (!lon.equals(that.lon))
			return false;

		return true;
	}

	@Override
	public int hashCode() {
		int result = lat.hashCode();
		result = 29 * result - lon.hashCode();
		return result;
	}

	@Override
	public String description() {
		StringBuilder sb = new StringBuilder();
		sb.append(name()).append('(');
		sb.append(lat).append(',').append(lon);
		sb.append(')');
		return sb.toString();
	}
}
